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* Add audit statement for `dkg-evrf` This doesn't cover the implementation, solely the academia and background. Also moves the existing audit of the `crypto` folder for organizational reasons. * Add files via upload
39 lines
1.9 KiB
Markdown
39 lines
1.9 KiB
Markdown
# eVRF DKG
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The DKG from the [eVRF paper](https://eprint.iacr.org/2024/397), extended with
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Verifiable Encryption premised on the same methodology present in the eVRF
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paper.
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The DDH-premised VRF is used, yet the different instantiation presented in
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section 6.4 premised on elliptic curve divisors. The one-round threshold DKG
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presented in section 4.2 is extended, with the following changes:
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- Any threshold of `t` participants may complete the DKG. This allows an
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adversary to bias the resulting key by choosing the set of participants, yet
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offers a robust protocol. The caller is able to choose between robustness and
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a lack of bias by completing the DKG with just `t` messages or by waiting for
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all `n`. If the caller does opt for robustness, the caller must ensure
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participants agree on the subset of participants who actually participated.
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- Communication of shares was prior defined as simply sending the share to the
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relevant participant, with no description of the channel. Now, a pair of
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ECDHs are performed on the embedded curve occurs (between the sender and the
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recipient's public key), whose `x` coordinates are summed for a random,
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uniform value (as an eVRF would). This value is used as a mask to encrypt the
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communicated secret share, with the zero-knowledge proof proving it's
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well-formed. This removes the need for a complaint round from the protocol,
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allowing it to truly complete (with all recipients holding valid shares) in
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just one round.
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For a gist of the verifiable encryption scheme, please see
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https://gist.github.com/kayabaNerve/cfbde74b0660dfdf8dd55326d6ec33d7. For
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security proofs and audit information, please see
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[here](../../../audits/crypto/dkg/evrf).
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---
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This library supports being run in no-std contexts with `alloc` when the `std`
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feature (on by default) is disabled. Due to the intensity of the ZK proofs,
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this isn't recommended, yet may be justified when _verifying_ posted proofs are
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correct.
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